sinfoera.com – MCQs, Mock Tests | Biochemistry Biochemistry MCQS PAPER SET 12

1 ï»¿Which of the following is incorrect with regard to antigen epitopes?

A An epitope may be shared by two different antigens B A protein molecule usually contains multiple epitopes C B cells bind only processed antigen epitopes D Epitopes may be linear or assembled

✅ Correct Answer: 3

2 Very low doses of antigen may induce

A hypersensitivity B immunological ignorance C low zone tolerance D low zone immunity

✅ Correct Answer: 3

3 During the lag period between antigen contact and detection of adaptive immunity,

A antigen is hidden from the immune system in macrophages B innate immune effectors are eliminating antigen C innate immunity blocks the activation of adaptive immune effector cells D new B and T cells with the appropriate antigen specificity must be produced in the bone marrow

✅ Correct Answer: 2

4 Lymphocytes are activated by antigen in the

A blood stream B bone marrow C liver D lymph nodes

✅ Correct Answer: 4

5 A pathogen can be a (n)

A agent that causes a disease B virus C bacteria D All of these

✅ Correct Answer: 4

6 CD antigens

A allow leukocytes to recognize antigen B are each expressed on only one cell type C are expressed on immune cells to mark them for separation D function as receptors for cytokine and CAMs

✅ Correct Answer: 4

7 A virus vaccine that can activate cytotoxic T cells must contain

A a high dose of virus particles B an adjuvant to stimulate T cell division C live virus D virus peptides

✅ Correct Answer: 3

8 The ability of an antigen to induce an immune response does not depend on the antigen's

A ability to enter the thyroid B degree of aggregation C dose D size

✅ Correct Answer: 1

9 The antibiotic penicillin is a small molecule that does not induce antibody formation. However, penicillin binds to serum proteins and forms a complex that in some people induces antibody formation resulting in an allergic reaction. Penicillin is therefore

A an antigen B a hapten C an immunogen D both an antigen and a hapten

✅ Correct Answer: 4

10 Which of the following immune cells would have an especially low count in a patient with advanced AIDS?

A Killer T lymphocytes B Helper T lymphocyte C B lymphocytes D None of these

✅ Correct Answer: 2

11 In cellular immunity, T lymphocytes are responsible for the recognition and killing of foreign invaders. The cells

A cytotoxic T lymphocytes (CTL) B killer T cells C both (a) and (b) D none of the above

✅ Correct Answer: 3

12 Plasma cells produce thousands of __________ that are released into the bloodstream

A antigens B antibodies C helper T cells D virus fragments

✅ Correct Answer: 2

13 If a person is vaccinated against a disease sometime in the past, which of the following is currently in your body?

A The disease organism itself and antigens for the disease organism B A very high level of antibodies against the disease antigens C Memory B lymphocytes for the antigen of this disease organism D All of the above

✅ Correct Answer: 4

14 What is a protein produced by host cells infected by viruses?

A Interferon B Histamine C Antiserum D Vaccine

✅ Correct Answer: 1

15 Polysaccharides on the surface of infecting microorganisms can also activate complement directly in the absence of

A antibody via the alternative pathway B antigen via the alternative pathway C antibody via metabolic pathway D none of the above

✅ Correct Answer: 1

16 Antibodies bound to an invading microorganism activate the complement system via

A classical pathway B metabolic pathway C Embden Meyerhof pathway D Entner-Doudoroff pathway

✅ Correct Answer: 1

17 The immune response to a booster vaccine is called a(n)

A cellular response B innate response C primary response D secondary response

✅ Correct Answer: 4

18 Immunological memory is due to

A short lived macrophage that can recognize specific pathogens B long lived B cells that secrete a specific antibody C long lived B cells that secrete a specific antigen D short lived helper T cells that signal macrophage to divide

✅ Correct Answer: 2

19 What is the result of an abnormal response of the immune system to part of a person's own body?

A Passive immunity B Cancer C An allergic response D An autoimmune disease

✅ Correct Answer: 4

20 What are the solutions prepared from weakened or dead microorganisms, viruses, or toxins that provide some immunity from diseases?

A Vaccines B Histamines C Drugs D Antibiotics

✅ Correct Answer: 1

21 During exposure to a foreign invader, there are more __________ present in the vertebrate body than before exposure

A antibodies B lymphocytes C macrophages and antigens D all of these

✅ Correct Answer: 4

22 To elicit the best antibodies to mouse MHC I, it should be injected into a

A goat B mouse of the same genetic background (strain) C mouse of a different strain D rat

✅ Correct Answer: 1

23 To detect a humoral immune response to influenza virus, it is possible to measure

A cytotoxicity of virus-infected cells in tissue culture B dividing T cells in the draining lymph nodes C plasma cytokine levels D serum antibody titer

✅ Correct Answer: 4

24 Which of the following is in the lymph nodes of a person battling a cold virus?

A Huge numbers of white blood cells B Trapped viruses that have been roaming the body C Lymph ducts that enter and exit the nodes and Lymph fluid D All of the above

✅ Correct Answer: 4

25 Immunogenicity

A depends on the ability of the native antigen to be presented by MHC B is usually a property of self antigens such as eye tissue C is not a property of antibodies D is not a property of haptens

✅ Correct Answer: 4

26 The HIV virus infects primarily

A brain cells B cells in the immune system C red blood cells D liver cells

✅ Correct Answer: 2

27 Chronic granulomatous disease results from a failure to perform oxidative burst. This deficiency would be most likely to interfere with

A CTL killing of viruses B dendritic cell activation to become a mature APC C infected cell processing of virus peptides D macrophage intracellular killing of bacteria

✅ Correct Answer: 4

28 Difficulties with somatic gene therapy arise from all of the following except

A GVHD caused by mature T cells in the transplanted cells B inserting a gene so that it will function properly C limited life span of more mature hematopoietic cells D transducing genetic material into stem cells

✅ Correct Answer: 1

29 A monoclonal antibody (mAb) specific for the 2,4-dinitrophenyl (DNP) hapten might also bind

A Leu or Ileu B His or Pro C Tyr or Phe D Ser or Thr

✅ Correct Answer: 3

30 Retinoblastoma is due to a mutation in a

A kinase B tumor supressor C cyclin D viral gene

✅ Correct Answer: 2

31 An autoimmune disease is

A AIDS B Measles C Lupus D Mumps

✅ Correct Answer: 3

32 If Class IIMHC is not expressed in the thymus, the resulting immune deficiencies would include all of the following except reduced

A alternative complement activation. B CD8 T cell-mediated cytotoxicity C macrophage activation to vesicular pathogens D IgG synthesis

✅ Correct Answer: 1

33 Specific translocations are associated with

A colon cancer B breast cancer C pancreatic cancer D some leukemias

✅ Correct Answer: 4

34 To treat HIV infections using drugs, the major problem is that

A the drugs that are good inhibitors cannot by synthesized B the drugs interfere with normal digestion C the virus particles with altered (mutant) proteases arise D the drugs are rapidly degraded

✅ Correct Answer: 3

35 The primary reason for AIDS, a deadly disease is that it

A is caused by a virus B is caused by a bacterium C destroys key components of the body's internal defense system D causes a breakdown of the body's inflammatory response

✅ Correct Answer: 3

36 A selective IgA deficiency would be expected to result in problems with

A bacterial infections B infections following dental work due to bacteria entering the bloodstream C mucosal pathogens D pathogens which can survive inside macrophages

✅ Correct Answer: 3

37 Combined cellular and humoral immune deficiencies result from lack of all of the following except

A a thymus B class II MHC C HIV infection of CD4+ T cells D transporter of antigen peptides (TAP)

✅ Correct Answer: 4

38 An example of an immunodeficiency disorder is

A thyroiditis B rheumatic fever C systemic lupus erythematosus D AIDS

✅ Correct Answer: 4

39 Bone marrow given to an infant with SCID must

A be irradiated to eliminate GVHD B contain mature T cells that can begin making immune responses immediately C come from a donor that shares some MHC alleles with the recipient D come from one of the child's parents

✅ Correct Answer: 3

40 X-linked hyper IgM syndrome, resulting in high levels of serum IgM and low levels of serum IgG, is caused by a defect in CD40L expression. The specific immune event that would be prevented by a defective CD40L would be

A activation of B cells by T-independent antigens B failure of B cells to provide co-stimulation for Th2 activation C failure of Th2 cells to provide co-stimulation for B cell isotype switching D failure of Th2 cells to provide co-stimulation for B cell proliferation

✅ Correct Answer: 3

41 DiGeorge's syndrome is characterized by the lack of a thymus The mouse model closest to this human disease would be a

A knock-out mouse for RAG-1 and RAG-2 B knock-out mouse for a thymus C nude mouse D recombinant mouse for CD3

✅ Correct Answer: 3

42 Which of the Rous sarcoma virus has a homologous cellular protein?

A c-src B v-src C v-ha-src D v-ha-ras

✅ Correct Answer: 1

43 Infants are most susceptible to bacterial infection due to low circulating levels of IgG

A in utero (before birth) B at 0-3 months of age C at 3-12 months of age D at 12-24 months of age

✅ Correct Answer: 3

44 The chemical, typically released by the body in an allergic response is

A histamine B allergens C antihistamines D perforins

✅ Correct Answer: 1

45 Small charged molecules, often biogenic amines function as

A hormones B neurotransmitters C both (a) and (b) D none of these

✅ Correct Answer: 3

46 SH2 domains specifically bind to

A phosphorylated serine residues B phosphorylated tyrosine residues C GDP D Ca2+

✅ Correct Answer: 2

47 In paracrine signaling, the signaling molecules affects only

A target cells close to the cell from which it was secreted B target cells distant from its site of synthesis in cells of an endocrine organ C both (a) and (b) D none of the above

✅ Correct Answer: 1

48 Simple nerve reflexes use signaling molecules called

A neurotransmitters B nitric oxides C G proteins D proteases

✅ Correct Answer: 1

49 Which of the following is not a type of signaling

A Testosterone B Insulin C Thyroxin D Adenylate cyclase

✅ Correct Answer: 4

50 Self-phosphorylation is an excellent mechanism for triggering specific catalytic function of the proteins involved in signal cascades because

A changes the shape and thus the enzymatic activity of the proteins involved B makes the receptor more likely to capture the signaling, molecule C allows hydrophilic signaling molecules to cross the plasma membrane D None of the above

✅ Correct Answer: 1

51 Which of the following statements about G proteins is false?

A They are involved in signal cascades B They bind to and are regulated by guanine nucleotides C They become activated when bound to GDP D They must be active before the cell can make needed cAMP

✅ Correct Answer: 3

52 When a __________ reaches its __________ , there is a specific means of receiving it and acting on the message. This task is the responsibility of specialized proteins called __________ .

A signaling molecule; receptor; G proteins B signaling molecule; target cell; G proteins C signaling molecule; target cell; receptors D kinase; receptor; proteases

✅ Correct Answer: 3

53 Why is it that inhaling nitric oxide reduces blood pressure only in the lung tissue and not elsewhere in the body*?

A Because other body tissues use a different signaling molecule B Because nitric oxide cannot cross cell membranes and enter the blood C Because nitric oxide breaks down quickly and thus cannot travel far D None of the above

✅ Correct Answer: 3

54 Which of the following comes under the category of cell surface receptor?

A Enzyme linked receptors B Ion-channel linked receptors C G protein linked receptors D All of these

✅ Correct Answer: 4

55 Which of the following is true about a hydrophilic signaling molecule?

A Its receptor is located in the cytosol of the target cell B It might trigger a signal cascade that causes some effect in a cell C Since it can enter the cell, it directly affects some specific cell process D It is a steroid

✅ Correct Answer: 2

56 cAMP and cGMP are derived from

A ATP and GTP by the actions of adenylate cyclase and guanylate cyclase respectively B GTP and ATP by the actions of adenylate cyclase and guanylate cyclase respectively C ATP and GTP by the actions of guanylate cyclase and adenylate cyclase respectively D none of the above

✅ Correct Answer: 1

57 Nitroglycerin has long been administered to human patients suffering from chronic chest pain (angina). This medication works because it

A mimics the action of signal receptors B is broken down into hormones that affect the heart C interferes with chemical cascades that trigger contraction of heart muscle D breaks down into nitric oxide, which increases blood flow to the heart

✅ Correct Answer: 4

58 If a disease of the blood vessels caused the endothelial cells of the vessel to die, what effect would that have on the cellular activities associated with vasodilation?

A Nitric oxide would no longer be produced B Smooth muscle cells could not be made to relax C blood flow and reduce blood pressure D All of the above

✅ Correct Answer: 4

59 In terms of cell communication, what do bacterial pathogens such as cholera and anthrax have in common?

A They destroy the receptors for key signaling molecules B They prevent the production of key signaling molecules C They alter the chemical structure of key signaling molecules D They block the normal functioning of signal transduction mechanisms

✅ Correct Answer: 4

60 What is the name of the protein signaling molecule that alters glucose uptake, and where would its receptors be located?

A Insulin; many different cell types that use glucose for fuel B Insulin; beta cells of the pancreas C PDGF; the blood D NGF; the nerves involved in simple reflexes

✅ Correct Answer: 1

61 In the signal transduction mechanism known as protein phosphorylation

A the signaling molecule binds to a surface receptor B receptor kinases play a key role in triggering the signal cascade C phosphorylated proteins act with enzymes to trigger the signal cascade D All of the above

✅ Correct Answer: 4

62 Cell signaling can be classified into

A three distinct types based on the distance over which the signaling molecules act B two distinct types based on the distance over which the signaling molecules act C three distinct types based on the signaling molecules D none of the above

✅ Correct Answer: 1

63 Which of the following statement is correct?

A Cell communicate with one another in multicellular organisms using extracellular signaling molecules or hormones B Cell communicate with one another in unicellular organisms using extracellular signaling antigen and antibody C Cell communicate with one another in multicellular organisms using intracellular signaling molecules only D Cell communicate with one another in unicellular organisms using intracellular signaling antigen and antibody

✅ Correct Answer: 1

64 In vasodilation, proper nerve signals sent to blood vessels cause

A the release of nitric oxide from endothelial cells B relaxation of smooth muscle cells C reduced blood pressure D All of the above

✅ Correct Answer: 4

65 A cell is known to respond to a particular signaling molecule. Which of the following must be true of this cell?

A It is in the heart muscle B It is also the site of production for the signaling molecule C It contains the receptor for the signaling molecule D It is incapable of signal transduction

✅ Correct Answer: 3

66 The enzyme that catalyzes the splitting of PIP2 into two molecules of inositol triphosphate (IP3) and diacylglycerol in cell signaling, is

A phosphokinase C B phospholipase C C phosphodiesterase C D lipokinase

✅ Correct Answer: 2

67 The binding of ligands to many G-proteins linked receptors leads to shortlived

A increase in the concentration of certain intracellular signaling molecules called second messenger B decrease in the concentration of certain intracellular signaling molecules called second messenger C increase in the concentration of certain extracellular signaling molecules called first messenger D decrease in the concentration of certain extracellular signaling molecules called first messenger

✅ Correct Answer: 1

68 Which of the following processes involve the combining of a message from one signaling molecule with that of another to either enhance or inhibit a cellular effect?

A Signal transduction B Signal reception C Signal integration D Signal amplification

✅ Correct Answer: 3

69 A signal cascade induced by adrenaline or thyroxine

A must begin with receipt of the signal molecule by a surface receptor B involves the activation of a G protein C results in the activation of a sequence of enzymes needed for the cell effect D all of the above

✅ Correct Answer: 4

70 Which of the following is a second messenger?

A lnositol 1,4,5-triphosphate B Diacyl glycerol C Phospholipase C D Both (a) and (b)

✅ Correct Answer: 4

71 Which of the following statement is incorrect?

A The principal lipophilic hormones that binds to receptors located in the plasma membranes are prostaglandins B Prostaglandins are synthesized from arachidonic acid C Prostaglandins act as paracrine signaling molecules D None of the above

✅ Correct Answer: 4

72 Two key organizing principles for large multicellular organisms are

A prokaryotic cell structure and cell specialization B cell specialization and communication between cells C communication between cells and simple nerve reflexes D simple nerve reflexes and cell specialization

✅ Correct Answer: 2

73 Which of the following is a hormone whose action requires a cell surface receptor?

A Nitric oxide B Progesterone C Adrenaline D Growth factors

✅ Correct Answer: 3

74 The hormone or ligand can be considered as

A first messenger B second messenger C both (a) and (b) D none of these

✅ Correct Answer: 1

75 The major second messengers are

A cAMP B cGMP C DAG D All of these

✅ Correct Answer: 4

76 he signaling molecules called steroid hormones

A are made in one location of the body but have their effects some distance away B are hydrophilic and so cannot penetrate the plasma membrane C bind to cell surface receptors to trigger chemical cascades D never enter the blood of humans

✅ Correct Answer: 1

77 The accepted hypothesis for DNA replication is

A conservative theory B dispersive theory C semi-conservative theory D evolutionary theory

✅ Correct Answer: 3

78 When DNA polymerase is in contact with guanine in the parental strand, what does it add to the growing daughter strand?

A Phosphate B Cytosine C Uracil D Guanine

✅ Correct Answer: 2

79 Telomeres are usually rich in which nucleotide?

A Adenine B Guanine C Thymine D Cytosine

✅ Correct Answer: 2

80 Which is the largest among the followings?

A Nucleotide B Nitrogenous base C Phosphate D Carbon

✅ Correct Answer: 1

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Biochemistry MCQS PAPER SET 12